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AJR Am J Roentgenol. 2014 Mar;202(3):W247-53. doi: 10.2214/AJR.13.10917.

Apparent diffusion coefficient for prostate cancer imaging: impact of B values.

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  • 11 School of Electronic and Information Engineering, Beijing Jiaotong University, No. 3 Shangyuancun, Haidan District, Beijing, China, 100084.

Abstract

OBJECTIVE:

The purpose of this article is to investigate the effect of b values on apparent diffusion coefficient (ADC) values estimated from 1.5-T diffusion-weighted MRI (DWI) of the prostate acquired with an endorectal coil in distinguishing prostate cancer from normal-tissue regions of interest (ROIs) and the correlation of ADC values with the tumor Gleason score.

MATERIALS AND METHODS:

Pretreatment DWI studies were analyzed retrospectively in 51 consecutive patients with prostate cancer with either two (b=0 and 1000 s/mm2; n=26 patients) or five (b=0, 50, 200, 1500, and 2000 s/mm2; n=25 patients) b values. In 45 normal peripheral-zone ROIs and 65 prostate cancer ROIs (14 in the central gland), ADC values were estimated by use of several combinations of two or five b values and a monoexponential model. We used the area under the receiver operating characteristic curve to characterize the effectiveness of ADC values in distinguishing prostate cancer from normal-tissue ROIs, and we calculated Spearman rank-order correlation between ADC values and the Gleason score.

RESULTS:

ADC values were often significantly different (p<0.001) when estimated from different combinations of two or five b values. However, except when both b values were less than or equal to 200 mm2/s or greater than or equal to 1500 mm2/s, the AUC value for distinguishing prostate cancer from normal-tissue ROIs was similar (0.88-0.93). The correlation coefficients between ADC values and the Gleason score were between -0.30 and -0.68.

CONCLUSION:

The choice of b values can significantly affect ADC estimates. ADC values can produce a similar discriminant performance in distinguishing prostate cancer from normal-tissue ROIs and in correlation with the Gleason score, but an appropriate ADC cutoff value needs to be selected specifically for each b-value combination.

PMID:
24555621
[PubMed - indexed for MEDLINE]
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